In the year 1199 when John succeeded his brother Richard as king of England, and soon began to consider Isabella as a suitable bride. Although John was already married to Isabel of Gloucester, ten years of marriage had not produced anything in the way of any offspring. So John promptly had this marriage annuled and arranged for the abduction of the French Isabella. They were duly married on the 24th August 1200 at Bordeaux. Naturally John hoped that a new wife would provide him with the necessary heirs and secondly that a French wife might make him more acceptable to his French subjects. (Who rather preferred the claims of his nephew Arthur of Brittany as king.)

Unfortunately for John this marriage was to come at a heavy price. Isabella had earlier been betrothed to Hugh de Lusignan, the Count of la March, who was not, as you might imagine, too pleased that his intended had been snatched way in this manner. He duly complained to the French king Philip II, who was similarly annoyed that John had failed to obtain his permission for the match and therefore declared all of John's French lands forfeit. The resulting conflict between John and his French counterpart resulted in the loss of Normandy, with further consequences as regards John's relationship with hs English subjects.

In the course of their marriage, Isabella bore five children, the eldest of whom became king Henry III of England on his father's death. There was another son named Richard who became Earl of Cornwall and three daughters, the youngest of whom, Eleanor would later marry Simon de Montfort.

When John died in 1216, Isabella was still in her twenties. Now a widow, Isabella returned to France where she married a Hugh de Lusignan; not the Hugh de Lusignan whom she was earlier betrothed to, but rather his son. By this marriage Isabella had a further eleven children, who were of course all half brothers and sisters to Henry III.